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Biomedical subjects

K K Talwar

Publications and source records attributed to K K Talwar.

At least 109 records · Page 6Linked to original sources
PubMed1985

Adaptation of human atrial muscle repolarisation after high rate stimulation.

We analysed the effect of a sudden change from a high rate of stimulation to a "physiological" rate upon the repolarisation of human atrial muscle. Microelectrode technique was used to study the effect upon the action potential (AP) recorded from myocardial specimens obtained during open heart surgery in nine patients. Suction electrodes were used to record monophasic action potentials (MAPs) in 12 patients undergoing electroconversion of atrial fibrillation. The abrupt change from 30 min of high-rate stimulation of the atrial specimen to a pacing rate of 60 per min resulted in a successive prolongation of the atrial myocardial AP duration so that 50% of the prolongation was reached after 3 min according to an exponential analysis. A similar prolongation of repolarisation was seen in the MAP recordings after conversion of atrial fibrillation to sinus rhythm and during regular atrial stimulation at a rate of 100 per min. In these recordings, the time needed to reach 50% of the prolongation of the MAP after DC conversion was about 7 min. The findings demonstrate that human atrial muscle undergoes an adaptation of repolarisation after abrupt slowing from a fast stimulation rate. A steady-state level of the AP or MAP duration is reached 10 to 15 min after the change of rate. Together with earlier studies, these experiments indicate, that when right atrial MAP recording is done for assessment of the likelihood of the patient's remaining in sinus rhythm after conversion of atrial fibrillation, the recording must be made within a few minutes of the conversion.

Action Potentials↗
PubMed1984

Spatial vectorcardiography in the Wolff-Parkinson-White syndrome: correlation with epicardial mapping findings.

The spatial vectorcardiograms (VCG) of 13 patients with WPW syndrome due to single accessory pathways were analyzed and correlated with the excitation analysis obtained on epicardial mapping. The azimuth angle of the initial 10 ms cardiac vector was greater than + 90 degrees (directed right and anteriorly) in patients with a left ventricular free wall; it ranged between 0 degree to 90 degrees (left and anteriorly) in those with a left or right paraseptal free wall and was -30 degrees (left and posteriorly) in one patient with a right ventricular free wall location. The elevation angle of the initial 10 and 20 ms cardiac vector was either zero or positive (inferiorly directed) in those with right and left ventricular free wall pathway. Among six patients with a paraseptal location, the elevation angle was negative (superiorly directed) in four and positive in two. Both the patients with a clockwise inscription of a QRS loop in the horizontal plane (HP) had pathways located to the left ventricle. Among the paraseptal group, at surgery, the accessory pathway could not be excised in two in spite of dissection very close to the IV (interventricular) septum. The elevation angle in both these patients was markedly negative (-45 degrees and -62 degrees) in contrast to the other in whom surgical excision was successful.+

Adolescent↗
PubMed1983

Immunologic studies in infective endocarditis.

Some immunologic changes in patients with infective endocarditis were measured during therapy with antibiotics. T cells and C3 levels were low in 29 and 59% of the subjects, respectively. The circulating immune complexes were high and showed a negative correlation with serum C3 levels. Teichoic acid antibodies with titer of above 5 were generally seen only in cases of bacteremia in which endothelial damage had taken place. The antibody was specific for gram-positive organisms because it was negative in gram-negative bacteremia. The antibody showed a fall during treatment and hence could be used to monitor efficacy of antibiotic therapy.

Adolescent↗
PubMed1983

Electrophysiological effects of lidocaine in acute myocardial infarction with bifascicular block or complete A-V block.

Electrophysiological effects of lidocaine were studied in 27 patients with acute myocardial infarction complicated by bifascicular block (group I: 20), and complete A-V block (group II: 7). Lidocaine was administered intravenously in bolus doses of 100 mg each at intervals of 10 min. In group I, there was no significant change in the heart rate (Before (B) = 84.85 +/- 24.19, After (A) = 87.25 +/- 20.26 beats/min) intra-atrial (PA) conduction time (B = 25 +/- 6.18, A = 27.22 +/- 6.69 ms), A-V nodal (AH) conduction (B = 111.5 +/- 56.12, A = 111.5 +/- 56.5 ms) or His bundle to ventricular (HV) activation time (B = 59.5 +/- 19.32, A = 61.25 +/- 18.62 ms) after lidocaine administration. In group II, 2 patients reverted to sinus rhythm, one with 1:1 conduction and the other with type II Wenckebach's block, with being prepared for the study, but both had complete A-V block within 1 h of the His bundle electrogram recordings. Of the remaining 5 patients, 4 had supra and 1 infra His A-V block. After lidocaine, 2 patients developed asystole. In the remaining 4 patients, there was no change in the escape rate or various conduction intervals.

Aged↗
PubMed1977

Serum levels of thyrotropin, thyroid hormones and their response to thyrotropin releasing hormone in infective febrile illnesses.

In 25 patients suffering from fever of infection, serum levels of thyrotropin (TSH), thyroxine (T4), triiodothyronine (T3), and thyroxine binding globulin (TBG) were estimated on two consecutive days during the febrile period and again 3 to 10 days after the fever had subsided. The serum TSH and T3 responses to 100 mug iv TRH were also studied during fever. Hormones were estimated by specific radioimmunoassays and TBG by radioligand binding assay. As compared with age and sex matched normal controls, patients with fever of infection had significantly lowered levels of total serum T3 and TBG. The serum TSH and total T4 concentrations were not significantly altered. During fever both % FT4 and absolute FT4 were significantly elevated, whereas only % FT3 was significantly increased and due to lowered serum total T3 levels the absolute FT3 were not significantly altered as compared to that in normal subjects. After the fever had subsided, the serum T3 levels returned to normal and the serum TBG levels increased. There was no correlation between basal serum levels of T3 and TSH during fever. Although in response to iv TRH the mean rise in serum TSH during fever was comparable to that in normal subjects, the overall TSH response showed an inverse correlation with serum TT3 levels. Following iv TRH there was a significant increase in serum T3 levels and the T3 response in fever was comparable to that in normal subjects. These data suggest that hormone secretion by the thyroid and its responsiveness to endogenous TSH are maintained during fever. The lowered T3 levels are not suggestive of a hypothyroid state, but perhaps could be due to decreased peripheral conversion of T4 to T3 and to decreased binding of T3 to serum proteins. The exact mechanism or significance of these alterations in thyroid function during febrile illness remains to be elucidated.

Adolescent↗
PubMedDate not supplied

Pulmonary varix associated with mitral valve disease.

A case of pulmonary varices with mitral valve disease is presented with a detailed review of the literature. Two distinct categories of the disease, with and without left atrial hypertension, are emphasized.

Adolescent↗
PubMedDate not supplied

Coronary artery to pulmonary artery collaterals in nonspecific aortoarteritis involving the pulmonary arteries.

We report a patient with nonspecific aortoarteritis (Takayasu's disease) in whom occlusion of the right upper lobe pulmonary artery was associated with collateral flow from the left circumflex coronary artery. Coronary to pulmonary artery collaterals are rare in this disease but have important clinical implication because of their ability to produce coronary steal and myocardial ischemia. Awareness of these pathways is essential for their detection in patients with angina-like symptoms and for differentiation of myocardial ischemia due to direct coronary artery involvement by this disease.

Adult↗
PubMedDate not supplied

Renal vein injury during percutaneous transluminal renal angioplasty in nonspecific aortoarteritis.

Percutaneous transluminal renal angioplasty of a right renal artery stenosis in a patient with nonspecific arteritis (Takayasu's arteritis) was performed for the treatment of renovascular hypertension and led to ipsilateral renal vein perforation and massive retroperitoneal bleeding. The mechanism of injury and its relationship to nonspecific arteritis remains obscure. Awareness of this potentially lethal complication is essential because early diagnosis is mandatory for definitive management.

Adolescent↗
PubMedDate not supplied

Angiographic morphology in nonspecific aortoarteritis (Takayasu's arteritis): a study of 126 patients from north India.

We have studied the angiographic morphology of nonspecific aortoarteritis, or Takayasu's arteritis, in 126 patients who underwent total aortoarteriography by intravenous or intraarterial digital subtraction angiography (DSA). Steno-obstructive lesions were seen in 124 (98.4%) patients and commonly involved the abdominal aorta (76.1%), the renal (67.5%), and the subclavian (56.3%) arteries. They were usually symptomatic. Aneurysms were seen in 16 (12.7%) patients and predominantly involved the descending thoracic aorta (62.5%). They were clinically silent. Localized saccular aneurysms (75%) were more common than the fusiform variety. Asymptomatic pulmonary artery involvement was seen in 11 patients (n = 74; 14.9%). Right lung involvement (72.8%) was more common, usually as a stenosis or occlusion of a lobar branch in the upper zone. Intravenous DSA was usually adequate for establishing the diagnosis. In this population a distinct pattern of involvement and the young age at diagnosis were remarkable.

Adolescent↗